Roof support assemblies



May 23, 1967 [3, BQLTQN ET AL 3,320,858

ROOF SUPPORT ASSEMBLIES Filed June 17, 1364 FIG.

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Invsarqroa 3 P -LA: H-H. B LTo/J i /MK PAWLU Bv lCUAEL PoTTs M ATTORNEYS United States Patent 3,320,858 ROOF SUPPORT ASSEMBLIES Douglas Herbert Hewlett Bolton, Winchcombe, Michael Charles Potts, Prestbury, and Frank Pawling, Charlton Kings, England, assignors to Dowty Mining Equipment Limited, a British company Filed June 17, 1964, Ser. No. 375,750 Claims priority, application Great Britain, June 21, 1963,

Claims. (Cl. 911) This invention relates to roof support assemblies, suitable for use in mines, in which the roof supports are advanceable in a predetermined sequence.

In such roof support assemblies, the roof supports may be controlled from a remote position in such a manner that the roof supports are selected in a predetermined sequence for advancing operations by manual or automatic means at the remote position, as described for example in US. Patent No. 3,285,015. On the other hand, the advancing operation of each roof support may be initiated by the receipt of a signal from the previous roof support in the series, it being preferable that such a signal should only be emitted from the previous roof support when the previous roof support has satisfactorily completed its advancing operation. Examples of this arrangement are described in U.S. Patents Nos. 3,240,125 and 3,228,199.

Roof supports usually include one or more fluid-pressure-operated props operable to support the roof and a fluid-pressure-operated advancing jack secured to an anchorage, for example another roof support or a conveyor extending along the working face of a mine. The props usually have to be released from a roof-supporting condiiton before the roof support can be advanced by the jack and, after the roof support has advanced, the props are reset to a roof-supporting condition. Such a roof support may fail during an advancing operation by failing to advance from one position to another position or by failing to resume supporting the roof.

In mining operations, it is most important that the roof supports undergo satisfactory advancing operations in the predetermined sequence, and it is an object of this invention to provide a roof support assembly in which the failore of a roof support during an advancing operation is indicated.

The present invention provides a roof support assembly including a series of roof supports advanceable in a predetermined sequence, a first signalling means associated with at least some of the roof supports in the sequence to produce a signal of one type as each of these roof supports undergoes an advancing operation, a second signalling means associated with at least some of the roof supports in the sequence to produce a signal of another type as each of these supports undergoes an advancing operation, the first and second signalling means being associated with the roof supports in such a manner that, when the roof supports advance in the predetermined sequence, the two types of signals are produced in a predetermined intermingled order, and checking means responsive to the signals of both types and arranged to indicate the occurrence of an incorrect order of receipt of the two types of signals.

An incorrect order of receipt of the two types of signals will occur if a roof support fails during an advancing operation. The occurrence of an incorrect order of receipt of the two types of signals may be indicated by the stopping of the advancing sequence of the series of roof supports or by an audible warning. If the advancing sequence has stopped, it may be arranged that the advancing sequence can be restarted by an operator who will therefore have noted that a roof support has failed during an advancing operation.

One type of signal may be derived from the supply of fluid to or the return of fluid from the roof supports. The other type of signal may be an electric signal.

One embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, of which FIGURE 1 is a diagrammatic view of mining apparatus with the hydraulic and electrical connections omitted, and

FIGURE 2 is a diagrammatic view of checking means responsive to signal of two types.

With reference to the accompanying drawings, coal mining apparatus includes a conveyor 1 extending along the working face 2 of a mine and a cutting machine 3 which passes along the working face 2 and is situated between the working face 2 and the conveyor 1. The mining apparatus also includes a series of roof supports 4 located on the opposite side of the conveyor 1 to the cutting machine 3 and working face 2. Each roof support 4 includes a ground-engaging sole beam 5 carrying a roof beam (not shown). Each roof support 4 also includes a double-acting hydraulically-operable jack 7 connected between the sole beam 5 and the conveyor 1. The jack 7 can be operated to advance the conveyor 1 relative to the roof supports 4 (when assisted by other jacks 7) or to advance the roof support 4 towards the conveyor 1 after the props 6 have been released from the roof.

The roof supports 4 are advanceable in a predetermined sequence. As mentioned previously, the roof supports 4 may be controlled from a remote position in such a manner that the roof supports 4 are selected in a predetermined sequence for advancing operations by manual or automatic means, as described for example in US. patent application No. 238,587 in which the hydraulic props and jack of each roof support are controlled by electrical means, and electric signals of the extension of the jack and the hydraulic pressure in the props are obtained at the remote position, these signals being received at the remote position only from the roof support actually selected for an advancing operation. On the other hand, the advancing operation of each roof support may be initiated by the receipt of a signal from the preceding roof support in the series, such a signal being emitted from the previous roof support only when the previous roof support has satisfactorily completed its advancing operation, as described for example in U.S. Patent 3,240,125.

Thus the roof supports 4 are hydraulically-operated and advanceable in a predetermined sequence. A hydraulic pressure line connected to a source of hydraulic fluid under pressure will be connected by branch lines to the props and jack of each roof support, and a return line for hydraulic fluid will be similarly connected. When each roof support undergoes an advancing operation, the hydraulic pressure and rate of flow of fluid in the supply and return lines varies, due to the release of the props 6, the operation of the jack 7 and the re-setting of the props 6. US. Patent 3,217,603 describes how the variations in the fluid conditions in the supply and return lines can be utilised as a signaling means, hereinafter referred to as a first signaling means to provide a signal when each roof support 4 undergoes an advancing operation. In this embodiment of this invention, such a signal is utilised as one of the two types of signals. In particular in this embodiment the signal is a fluid-pressure-signal caused by variations in pressure in the supply line. In FIGURE 2 the supports are shown in block form as having fluid pressure signal means 4A and electric signal means 4B referred to as the first and second signaling means.

The other type of signal is an electrical signal from the jack 7 of every fourth roof support 4, and it is so arranged that this signal is derived from the second signaling means and is emitted only when the jack 7 reaches its fully contracted state, that is to say only when the roof support has advanced fully from one position to another. In the arrangement described in U.S. Patent No. 3,285,015, the selected roof support sends to the remote position a signal of jack length and, when the jack length reaches its minimum, this signal is arranged to provide the previously. mentioned electrical signal to indicate that the roof support has fully advanced. If the arrangement described in U.S. Patent No.3,240,125 is used, the full contraction of the jack is arranged to supply an electrical signal, and the satisfactory resetting of the props which causes the fiuid-pressure signal to be passed on to the next roof support is arranged to cancel the electrical signal.

Thus, when each roof support undergoes an advancing operation, a fluid-pressure signal is given by each roof support as it undergoes an advancing operation, and an electric signal is given by every fourth roof support as it undergoes an advancing operation.

FIGURE 2 shows the checking means responsive to both types of signal. The fluid-pressure signal is supplied by the fluid signal means 4A of each support through a conduit to one side of a piston 8 slideably mounted in a cylinder 9. A spring 11 acts on the piston 8 in the opposite direction to the force exerted on the piston 8 by the fluid-pressure signal. The strength of the spring 11 is so arranged that, when substantially full pressure is present in the supply line, the piston 8 is retained in the position shown in the drawing and, when during an advancing operation of a roof support the pressure falls to a minimum (for example when the props 6 are resetting), the spring 11 moves the piston 8 and a piston rod 34 to the left to act upon a ratchet 12 and rotate a shaft 13 carrying the ratchet 12 through 90". Thus each time a roof support undergoes an advancing operation, the shaft 13 is rotated through 90 by the fluidpressure signal as the props 6 of the roof support 4 reset.

The shaft 13 carries an electrical contact 14 which rotates over a disc 15 carrying an arcuate electrical contact 16 engageable by the rotatable contact 14. The contact 1 6 is connected through a pair of normally-open relay contacts 17, 1 8 to one terminal of an electrical power supply 21. The rotatable contact 14 is connected through a relay coil 22 to the other terminal of the electrical power supply 21.

When energised, the relay coil 22 closes a pair of norrnally-open contacts 23, 24. The contact 23 is connected through a hold-on coil 25 to one terminal of the power supply 21 and the other contact 24 is connected through an audible warning device 26 and a normally-closed switch 27 to the other terminal of power supply 21.

A relay coil 28 operable to close the relay contacts 17, 18 is connected to one terminal of an electrical power supply 29 and is connected through a normally-open switch 31 to the other terminal of the power supply 29. The switch 31 is arranged to be closed by the electrical signal which operates relay winding 31A and indicates the full advance of a roof support.

When the roof supports 4 are advanced in the predetermined sequence and a roof support 4 which supplies an electrical signal and a hydraulic signal has just completed an advancing operation, the rotatable contact 14 is in position A shown in FIGURE 2, and switch 31, relay contacts 17, 18 and relay contacts 23, 24 are open.

As the first subsequent roof support 4 undergoes an advancing operation, the fluid-pressure signal from it actuates the piston 8, and the shaft 13 and rotatable contact 14 are rotated through 90 to bring the rotatable contact 14 to position B in which it engages arcuate contact 16. However, the relay contacts 17, 18 are open so the circuit is not completed.

The fluid-pressure signal from the second roof support 4 causes rotation of the rotatable contact14 to position C in which the rotatable contact 14 still engages arcuate contact 16. Relay contacts 17, 18 are still open however.

The fluid-pressure signal from the third roof support 4 causes rotation of the rotatable contact 14 to position D in which the rotatable contact 14 is no longer in engagernent with the arcuate contact 16.

As the fourth roof support 4 undergoes an advancing operation, an electrical signal and then a fluid-pressure signal is received from it. The electrical signal causes switch 31 to close momentarily, resulting in energisation of the relay coil 28 and consequent closure of relay contacts 17, 18. Since rotatable contact 14 is not in engagement with arcuate contact 1 6, the closure of relay contacts 17, 18 has no effect, and when switch 31 reopens the relay contacts 17, 18 re-open. The subsequent fluid-pressure signal causes rotation of the rotatable contact 14 back to position A.

Thus, if the roof supports 4 advance in the predetermined sequence, the electrical and fluid-pressure signals are received by the checking means shown in FIGURE 2 in the correct order.

If a roof support fails during an advancing operation, the audible warning device 26 will be operated. For example, if the failed roof support 4 is one which should give a fluid-pressure signal only and fails to give this signal, the rotatable contact 14 will still be in position C when an electrical signal is received from a subsequent roof support 4. The electrical signal causes closure of switch 31 and consequent closure of relay contacts 17, '18. Thus relay coil 22 is energised with consequent closure of relay contacts 23, 24, and operation of the audible warning device 26. The hold-on coil 25 retains relay contacts 23, 24 in the closed position even though switch 31 and relay contacts 17, 18 subsequently open, and rotatable contact 14 subsequently moves on to position D to break its engagement with arcuate contact 16. Thus the audible warning device 26 continues to operate until an operator opens switch 27. The operator must also move the rotatable contact 14 to the correct position.

If the failed roof support 4 was one which should have given an electrical signal and a fluid-pressure signal and neither of these signals are received by the checking means, then when the next roof support 4 which gives both types of signal undergoes an advancing operation, the rotatable contact 14 will again be in position C and the audible warning device 26 will be operated.

The audible warning device 26 may also be arranged to prevent the advance of the fourth roof support 4 until an operator has taken some positive action.

The checking means may be located at any convenient position, for example in a road-way at one end of the working face of the mine adjacent the source of hydraulic pressure.

We claim:

1. A proof support assembly including a series of roof supports advanceable in a predetermined sequence, a first signalling means associated with at least some of the roof supports in the sequence to produce a signal of one type as each of these roof supports undergoes an advancing operation, a second signalling means associated with at least some of the roof supports in the sequence to produce a signal of another type as each of these roof supports undergoes an advancing operation, the first and second signalling means being associated with the roof supportsin such a manner that, when the roof supports advance in the predetermined sequence, the two types of signals are produced in a predetermined intermingled order, and checking means responsive to the signals of both types and arranged to indicate the occurrence of an incorrect order of receipt of the two types of signals.

2. A roof support assembly according to claim 1 wherein the roof supports are fluid-pressure-operated and the first type of signal is derived from the supply of fluid to or the return of fluid from the roof supports.

3. A roof support assembly according to claim 1 wherein the second type of signal is an electrical signal.

4. A roof support assembly according to claim 1 wherein the second type of signal is given when the roof support has fully advanced from one position to another position.

5. In a mining system having a plurality of sequentially operating roof support and conveyor advancing assemblies, a warning system for providing a Warning upon failure of the support and advancing assemblies to operate in the required sequence, comprising in combination: first and second signal means respectively responsive to an advancing operation of each assembly in first and second groups thereof; and sequence detection means coupled with said first and second signal means and automatically providing an indication of the receipt of signals therefrom in any sequence other than a predetermined intermingled sequence.

6. The system defined in claim 5 wherein said sequence detection means includes switch means having first and second members movable with respect to each other; drive means coupled with said switch means and to a first one of said signal means and changing the relative positions of said members in response to each operation of said first one of said signal means; energizing circuit means coupled with said switch means and controlled by the second one of said signal means; and Warning circuit means connected in circuit with said switch means and responsive to energization of said switch means when said members are in predetermined relative positions to provide a warning signal.

7. A system as defined in claim 6 wherein said switch means includes first and second contact members respectively connected to said first and second movable members and said drive means includes a rotatable shaft carrying one of said contact members, a first drive member connected to said shaft, and wherein said first signal means includes a reciprocating second drive member engageable with said first drive member to advance said shaft in step-wise fashion in response to sequential energization thereof.

8. A system as defined in claim 7 wherein said first signal means is fluid pressure responsive and includes conduit means connected thereto for providing variable pressure signals from the support and advance assemblies.

9. A Warning system for a mining apparatus having a plurality of hydraulic jacks operated in sequence with selected ones of the jacks in the sequence providing an electric signal upon proper operation, comprising in comb1nation: a first electrical contact member; a second electrical contact member; support means supporting said members for relative movement with said second member engageable with said first member only in selected relative positions of the members; hydraulic operated support advancing means coupled with said support means and responsive to intermittent pressurization to cause step-wise relative movement between said members; a first circuit means including a first switch connected in circuit between one of said contact members and a source of operating potential and responsive to an electric signal from one of said selected ones of said jack-s to energize one of said contact members; and warning circuit means including said contact members providing a warning signal when said contact members are engaged and said first switch means is closed.

:10. The system defined in claim 9 wherein said warning circuit means includes a self holding circuit and manually reset circuit means.

References Cited by the Examiner UNITED STATES PATENTS 2,355,092 8/1944 Meister 340-267 2,621,266 12/1952 Gretener 200-38 2,909,626 10/1959 Enssle ZOO-38 3,198,083 8/1965 Farr et a1. 911 3,198,973 8/1965 Short et al. ZOO-19 3,228,300 1/1966 Potts 911 MARTIN P. SCHWADRON, Primary Examiner. P. T. COBRIN, B. L. ADAMS, Assistant Examiners. 

1. A PROOF SUPPORT ASSEMBLY INCLUDING A SERIES OF ROOF SUPPORTS ADVANCEABLE IN A PREDETERMINED SEQUENCE, A FIRST SIGNALLING MEANS ASSOCIATED WITH AT LEAST SOME OF THE ROOF SUPPORTS IN THE SEQUENCE TO PRODUCE A SIGNAL OF ONE TYPE AS EACH OF THESE ROOF SUPPORTS UNDERGOES AN ADVANCING OPERATION, A SECOND SIGNALLING MEANS ASSOCIATED WITH AT LEAST SOME OF THE ROOF SUPPORTS IN THE SEQUENCE TO PRODUCE A SIGNAL OF ANOTHER TYPE AS EACH OF THESE ROOF SUPPORTS UNDERGOES AN ADVANCING OPERATION, THE FIRST AND SECOND SIGNALLING MEANS BEING ASSOCIATED WITH THE ROOF SUPPORTS IN SUCH A MANNER THAT, WHEN THE ROOF SUPPORTS ADVANCE IN THE PREDETERMINED SEQUENCE, THE TWO TYPES OF SIGNALS ARE PRODUCED IN A PREDETERMINED INTERMINGLED ORDER, AND CHECKING MEANS RESPONSIVE TO THE SIGNALS OF BOTH TYPES AND ARRANGED TO INDICATE THE OCCURRENCE OF AN INCORRECT ORDER OF RECEIPT OF THE TWO TYPES OF SIGNALS. 